Spreader shower for fabric belts of paper making apparatus

ABSTRACT

In a shower for cleansing the fabric on a paper machine, the shower nozzles are angled outward towards the edges of the fabric so as to spread the fabric and prevent ridges and wrinkles from forming. Preferably the nozzles are angled between 20* and 30* from the shower pipe and the shower is located after a driven roll.

United States Patent 1191 Truesdale et al. Aug. 20, 1974 [5 SPREADERSHOWER FOR FABRIC BELTS 1,989,435 1/1935 Wallquist 162/310 x OF PAPERMAKING APPARATUS 2,255,951 9/1941 Tomtlund 162/275 2,63l,058 3/1953lngham et al.,... .1 239/567 X Inventors: Robert Andrew Truesdale, D3,212,719 10/1965 Di Corpo 239/566 x 621.; John Gordon Buchanan, Pointe3,268,389 8/1966 Goyette 162/272 X Claire, Quebec, Canada [73] Assignee:J. W. 1. Ltd., Montreal, Quebec, FOREIGN PATENTS 0R APPLICATIONS Canada146,006 6/1954 Sweden 162/275 [22] Filed: Oct. 23, 1973 PrimaryExammerS. Leon Bashore 1 p N05 408,272 Assistant Examiner-Richard V.Fisher Attorney, Agent, or Firm-Alan Swabey; Robert E. [30] ForeignApplication Priority Data Mltche Dec. 13, 1972 Great Britain 57617/72 52us. c1 162/273, 134/15, 134/32, [57] ABSTRACT 162/275 239/566 In ashower for cleansin g the fabric on a paper ma [51] Int. Cl D21f 1/30,D2lf l/32 chine, the shower nozzles are angled outward towards [58]Field of Search 162/275, 274, 273, 199, the edges of the fabric so as toSpread the fabric and 162/ 272; 210/391 3; prevent ridges and wrinklesfrom forming. Preferably 209/380; 55/303; 239/559 567; the nozzles areangled between 20 and 30 from the 198/208 230; 134/15 32 shower pipe andthe shower is located after a driven ll. [56] References Cited m UNITEDSTATES PATENTS 10 Claims, 7 Drawing Figures 1,744,892 l/l930 Helinl62/275 A? /Z: /2 E;[% L e A .2 1.1,, ,c ?",/,"i, ","Yi\\ 1' l '1' 1 4x} x R L \f \f/ "mull-301 1 2 .7 3.830.691 snzmor a w wt k k v w w GdRad ed ouaAm annmwyu mamznmz 3.800.691

SHEET 2 0F 3 PRIOR ART SPREADER SHOWER FOR FABRIC BELTS OF PAPER MAKINGAPPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to improvements in the operation of a paper makingmachine. More specifically, this invention relates to a shower forsimultaneously spreading and cleansing the fabric endless belts of sucha paper machine.

2. Description of the Prior Art In the Fourdrinier section of apaper-making machine for example, a suspension of fibres is dischargedonto the upper surface of a moving endless fabric screen belt called aFourdrinier or forming wire. The belt travels over dewatering devicesand is subjected to considerable drag force as it is driven by its driveroll. The belt is therefore required to transmit considerable power tothe dewatering components and this develops a high tension in the upperrun immediately before the couch or drive roll. The high tension beforethe couch roll causes the belt to stretch slightly in the machine(lengthwise) direction, and, as is the case with most flexiblematerials, it will tend to contract in the crossmachine direction, i.e.,it will be narrowed in the width thereof, just as it runs onto the driveroll. The belt remains under high tension for most of its passage overthe drive roll but, just before it approaches the outgoing tangent ofthe roll, tension is gradually released and the belt willthen tend tocontract in the machine direction and to extend in the cross-machinedirection. Some longitudinal contraction occurs while the belt is stillin contact with the surface of the roll at the outgoing side andlocalized slippage of the belt on the surface takes place here causingrelative motion between fabric and roll in the longitudinal direction.Possibly, just before the belt emerges at the outgoing tangent of theroll a small increase in width also occurs which produces relativemotion between fabric and roll in the lateral direction. Then, asminimum tension is reached at the return section (lower run) of thebelt, an increase in width occurs while the belt is still under lateralrestraint from contact with the roll and this results in the formationof ridges and puckers.

Small temporary ridges or puckers are not harmful as long as they do notremain to spoil the flatness of the fabric as it passes over thedewatering section of the machine. As often happens, however,particularly in high speed machines where the power transmitted is highand the belt is wide, the ridges are especially pronounced and maybecome permanent so that they will adversely effect the smoothness ofthe belt in the dewatering section and so cause deformities in the paperthat is being produced. In the extreme, one or more permanent ridges canbecome sufflciently large to form creases which may extend around theentire length of the belt so that further use is not possible and thebelt must be removed from the paper machine.

In order to alleviate this ridging effect, a bowed spreader roll (notshown) may be installed near the point where the belt comes ofi thecouch roll. The roll is bowed in the general direction away from thecouch roll so that it provides a spreading out effect on the belt whichinduces lateral tension away from the center of the belt therebyminimizing or eliminating the ridges. However, these bowed rolls causemaintenance difficulties and are expensive to buy and install especiallyin the case of a wide paper making machine.

Although the problem of ridges is present to some extent where the beltsare metallic, i.e., comprised of bronze or stainless steel materials,the ridges are most pronounced when the belt is comprised of a syntheticfabric in which the stability in the width direction is not as great asin the case of the metallic fabric, so thatthe tendency to form ridgesis, therefore, greater when the belt is made of a synthetic fibre.

SUMMARY OF THE INVENTION The invention comprises a spreader shower foruse on a paper making machine wherein runs one or more endless fabricbelts; said shower comprising a series of nozzles joined by a pipe meansfor providing fluid under pressure to said nozzles; the said pipe beingdisposed across the width of said fabric and in substantially parallelalignment with and in close proximity to the surface of said fabric. Theinvention is characterized in that the nozzles are angled from said pipemeans so that fluid emerging under pressure from the nozzles is directedto impinge outwardly, substantially towards the edges in the lateraldirection, on said fabric. As a preferred embodiment, the invention maycomprise a spreader shower for use in the forming section of aFourdrinier paper making machine wherein said forming section comprisesa forming fabric in the shape of an endless belt having a high tensionupper run and a low tension lower run, as described heretofore; saidpipe being disposed between the upper and lower runs of the endless beltand extending along the width of the said belt and in substantiallyparallel alignment with the lower run; said nozzles being directed atthe lower run; characterized in that they are tilted from said pipemeans by an angle of less than whereby the nozzles are directed outwardtowards the edges in the lateral direction of said fabric.

The invention may also be applied to types of forming sections whichemploy endless fabrics other than the Four-drinier type, for exampleVertiforma, Bel- Baie Former, Papri-former, etc.

The invention is not limited to the forming section of a paper machinebut may also be adapted for use in the press section where oscillatingshowers having needle type jets are used to cleanse the conveying felts.In this adaptation a spreader shower may be used to replace one or moreworm rolls.

The spreader shower may also be used in the dryer section of a papermachine in locations where the fabric has a tendency to ridge.

Preferably, the nozzles of the spreader shower are directed outward atan angle between 10 and 60 with angles of 20 and 30 being the mostpreferred; the nozzles predominantly on the left hand side of the pipemeans being directed at the left hand edge of the Fourdrinier formingfabric, and the nozzles predominantly on the right hand side beingdirected at the right hand edge of the Fourdrinier forming fabric.

A high pressure oscillating shower on the low tension run of the fabric,normally used to unplug the mesh of the fabric of fibres, particles ofpitch, filler material, etc., can be modified, as above-described tofulfill the spreading function as well as its normal function. This is apreferred arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be betterunderstood by an examination of the following description together withthe accompanying drawings in which:

FIG. 1 illustrates the Fourdrinier section of a paper making machinehaving a couch roll drive.

FIG. 2 illustrates the drive section of a Fourdrinier having a separatedrive roll.

FIG. 3 is a perspective view of appropriate parts of a paper makingmachine to illustrate the problems the invention overcomes.

FIG. 4 illustrates one way of adapting the needle type shower inaccordance with the invention.

FIG. 5 illustrates another way of adapting the needle type shower inaccordance with the invention,

FIG. 6 illustrates the use of fan type shower nozzles and I FIG. 6aillustrates an end view of the fan type shower nozzles.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIGS. 1 and 3 in theFourdrinier section of a paper making machine, a Fourdrinier fabric inthe form of an endless belt 1, having an upper run la and a lower run1b, is driven over dewatering devices comprising foils 4, table rolls 5and suction boxes 7 by a couch drive roll-9 as is well known in the art.In order to overcome the problem of the belt becomming plugged by paperfibres, filler material, particles of pitch, etc., many mills install ahigh pressure, needle type oscillating shower pipe 11 on the bottom runlb of the belt 1. As needle type nozzles are used, the head mustoscillate back and forth across the fabric to insure cleansing of theentire fabric. These showers use high pressure jets of water to dislodgethe foreign materials from the fabric without adding an uneconomicalvolume of water to the white water solution which is circulated to theincoming paper stock. The shower is generally installed just after thecouch drive roll 9 in FIG. 1 embodiment. In an apparatus comprisingseparate couch and drive rolls, 9 and 13 respectively (see FIG. 2), theshower 11 is positioned after the drive roll 13. In each case the showeris positioned between the upper and lower run of the belt and the showernozzles are placed a few inches from and are directed towards the bottomrun. It has been found in practice that when the belt comprises asynthetic material instead of a metallic material, the mesh is moresubject to plugging and the role of the high pressure shower is veryimportant.

Ridges formed when the belt goes from the high tension area at the upperrun to the low tension area at the beginning of the lower run andemerges off the roll 9, are shown at 15 in FIG. 3.

Shower pipes adapted in accordance with the invention are illustrated inFIGS. 4 and 5. Referring to FIG. 4, the shower pipe 11 comprises aplurality of nozzles 12 each ejecting a needle spray or jet of a fluidmedium, usually water, 14. The nozzles are tilted by an angle from thepipe 11 in the lateral direction of the fabric so that the sprayimpinges on the bottom run of the belt lb at an angle 4) relative to thefabric. The noz-. zles to the left of the center nozzle 120 are directedat the left hand edge of the fabric whilethe nozzles to the right of 12care directed at the right handedge of the fabric. In this embodiment,the nozzles are equally spaced and each nozzle is angled at the sameangle, so that the horizontal component of force exerted by each nozzlewill be the same. If it is desirable to vary the force across the belt,the angle of tilt can be varied as shown in FIG. 5. Here, the angle oftilt gradually increases from each edge to the centre so that the angleof impingement varies from d) at the lateral edge in increasing angles(1), (1) to (b at the center nozzle. The nozzles are preferably angledidentically on both sides of the centre nozzle.

The force across the belt may also be varied by providing a variation innozzle size from the centre to each edge. Here again, nozzle size wouldvary identically on both sides of the center.

It is also within the scope of the invention to provide unequal spacingbetween nozzles if this is advantageous in specific cases.

Although needle type jets have generally been used for the cleansingshower, it has been discovered that other types of jets can be used toadvantage in accordance with the invention. Thus, fish tail (fan type)jets have been found satisfactory and indeed, as will be discussedbelow, can even be preferable to the needle type jets. In addition,although cleansing showers use only water, it has been discovered thatother fluids, such as air, and possibly steam, could be used inaccordance with the invention.

In the'above description, the angle 4) refers to the angle of tiltbetween the jet and the average plane of the fabric, measured in thecross direction. Localized deviations from the plane due to ridging ordeflection of the fabric resulting from the jet are not considered. Forthe purpose of this description the angle (b, representing the angle oftilt from the shower pipe, is also the angle of impingement on thecloth. In considering the question of preferred parameters, it is knownthat the horizontal component of force exerted by each nozzle varieswith the pressure of the fluid, the nozzle diameter and the angle ofimpingement of the fluid. Spreading can therefore be achieved with highpressure and small nozzle diameter (small volume of fluid) or lowpressure and large nozzle diameter (large'volume of fluid). In the casewhere the fluid is water the ratio of pressure and volume would normallybe selected only after considering the extra volume of water that couldefficiently be accommodated by the paper machine. It is usuallypreferred to minimize the quantity of water added to the system and thiscan be done by reducing nozzle size and using high pressure. In tests todetermine the preferred parameters, it was discovered that satisfactoryoperation is obtained with an angle of tilt d), ranging from 10 to 60.The most satisfactory results were obtained with angles of 20 and 30 andangles in between. The above results were obtained when the fluid usedwas either water or air.

In considering the question of preferred pressure, i.e., the pressureunder which water is supplied, it was postulated that this would dependupon the amount of water that could be accommodated which in turn woulddepend upon the nozzle size. In any case for a given nozzle size,pressure should be high enough to provide adequate lateral force forspreading the fabric.

Although a complete operating range of pressures I was not determined,satisfactory results were obtained with both air and water at pressuresof I00, 200, 400

and 600 psi. Nozzle sizes tried ranged from 0.036 inch to 0.067 inch indiameter.

A further parameter is the height of the nozzle above the fabric. lntests conducted in this regard, the height was taken from the tip of thenozzle to the fabric at right angles to the fabric, i.e., the verticalheight of the nozzle tips above the fabric.

It was found that, when water was the fluid, and at the testing heightsof 2 to 6 inches, the results were virtually independent of height. Withair as the fluid, on the other hand, it was found that if the nozzleswere more than one-half inch above the fabric, the lateral component offorce of the jet was seriously reduced so that an air shower shouldpreferably be kept no more than one-half inch above the fabric.

As discussed above, it is possible to use fish tail (fan type) nozzlesrather than the needle type nozzles in accordance with the invention. Inthis regard, the wide part of the fish tail jet could extend along thelength of the fabric. However, it has been found that it would beadvantageous to have the wide part of the jet extend along the width ofthe fabric as shown in FIG. 6. An end view of the fish tail (fan type)jet is shown in FIG. 6a. In this case, the spray from one nozzle shouldpreferably overlap the spray from an adjacent nozzle. Thus, it ispossible to cover the entire width of the fabric without oscillating theshower pipe 11 as is required when needle type nozzles are used.

It is also possible to rotate the nozzles of the fish tail arrangementso that cleansing takes place both along the width and the length of thefabric.

Although in the preferred embodiment, the cleansing shower is modifiedto fulfill both the functions of cleansing and spreading, it will beapparent that separate showers could be used for each of these purposes.Thus, as shown in FlG. 2, it would be possible to have a shower 11 forspreading the fabric, and a shower 25 for cleansing it. However, whenthe same shower is used for both purposes, the parameters must beadjusted to insure that both functions will be fulfilled. So,

although a smaller angle of tilt from the shower head may give a betterspreading action, it is possible that the cleansing action will beweakened. This must be taken into account when making and adjusting theapparatus in accordance with the invention.

In some cases where the deposition of pitch in the mesh of the fabric isa special problem and the pitch cannot be eliminated by any less thanthe full force of a needle shower placed at right angles to the surfaceof the fabric, it may be necessary to employ a separate cleansing showerin addition to a spreader shower. Or, if space is limited, to provide asingle shower head incorporating vertically directed nozzles forcleansing as well as angularly directed nozzles for eliminating ridges.

Although only a spray at right angles to the lengthwise direction of thebelt has been considered (14b in FIG. 1), it is also possible to anglethe nozzle so that it is at some other angle to the lengthwise directionof the belt, e.g., 14a and 140 in FIG. 1. It is preferred that the spraywill be directed against the direction of travel of the belt, i.e., thedirection 14c. However, if the nozzles are so angled, then a guardshould be included to insure that water does not splash back onto thecouch roll 9 from which it might undesirably be introduced into theformed paper through the underside of the belt as it travels onto thecouch.

Although several embodiments have been described above, this was for thepurpose of illustrating, but not limiting the invention. Variousmodifications, which will come readily to the mind of one skilled in theart, are within the scope of the invention.

We claim:

1. A paper making machine comprising at least one endless fabric belt,

said endless fabric belt being driven by a driving roll;

said endless fabric belt comprising a high tension portion and a lowtension portion,

said high tension portion being disposed in that portion of the beltpreceding said driving roll in the direction of travel of said belt,

said low tension portion being disposed in that portion of the beltfollowing said driving roll in the direction of travel of said belt,

and comprising at least one spreader shower,

said spreader shower comprising a series of nozzles joined by a pipemeans for providing fluid under pressure to said nozzles, said nozzlescomprising outlet ends, the outlet ends of said nozzles being directedat a surface of said endless fabric belt in said low tension portionthereof,

said pipe means being disposed across the width of said endless fabricbelt and in substantially parallel alignment with and in close proximityto said surface of said endless fabric belt,

each of said nozzles forming an angle of less than with said pipe means,and directed at said surface of said endless fabric belt,

the outlet ends of substantially all of said nozzles, lo-

cated in that portion of the shower extending substantially from thecenter of the pipe means to the left hand end thereof, being directedtoward the left hand edge of said fabric,

the outlet ends of substantially all of said nozzles, lo-

cated in that portion of the pipe extending substantially from thecenter of the pipe to the right hand end thereof, being directed towardthe right hand edge of said fabric,

whereby fluid emerging under pressure from the outlet ends of saidnozzles will impinge on said surface of said endless fabric belt andwill be directed substantially toward the lateral edges of said endlessfabric belt.

2. A paper making machine as defined in claim 1 wherein the anglebetween each said nozzle and said pipe means is between 10 and 60.

3. A paper making machine as defined in claim 2 wherein the anglebetween each said nozzle and said pipe means is between 20 and 30.

4. A paper making machine as defined in claim 1 where said fluid iswater.

5. A paper making machine as defined in claim 1 where said fluid is air.

6. A paper making machine as defined in claim 1 wherein said nozzlesprovide a fish tail type spray having a wide bottom impinging on saidfabric, the length of said wide bottom extending in the width of saidfabric; and wherein the bottoms of said sprays of adjacent nozzlesoverlap one another to thereby provide cleansing action oversubstantially the entire surface of the endless fabric belt.

7. A paper making machine as defined in claim 1 wherein said nozzlesprovide needle-type jet sprays, said spreader shower oscillating in thecross-machine direction of said endless fabric belt to provide cleansingaction over substantially the entire surface of the endless fabric belt.

8. A paper making machine as defined in claim 7 and further includingintermediate cleansing nozzles extending at an angle of 90 from saidpipe means in the direction of the surface of said endless fabric belt.

9. A paper making machine as defined in claim 1 wherein said endlessfabric belt comprises an upper run material.

1. A paper making machine comprising at least one endless fabric belt,said endless fabric belt being driven by a driving roll; said endlessfabric belt comprising a high tension portion and a low tension portion,said high tension portion being disposed in that portion of the beltpreceding said driving roll in the direction of travel of said belt,said low tension portion being disposed in that portion of the beltfollowing said driving roll in the direction of travel of said belt, andcomprising at least one spreader shower, said spreader shower comprisinga series of nozzles joined by a pipe means for providing fluid underpressure to said nozzles, said nozzles comprising outlet ends, theoutlet ends of said nozzles being directed at a surface of said endlessfabric belt in said low tension portion thereof, said pipe means beingdisposed across the width of said endless fabric belt and insubstantially parallel alignment with and in close proximity to saidsurface of said endless fabric belt, each of said nozzles forming anangle of less than 90* with said pipe means, and directed at saidsurface of said endless fabric belt, the outlet ends of substantiallyall of said nozzles, located in that portion of the shower extendingsubstantially from the center of the pipe means to the left hand endthereof, being direCted toward the left hand edge of said fabric, theoutlet ends of substantially all of said nozzles, located in thatportion of the pipe extending substantially from the center of the pipeto the right hand end thereof, being directed toward the right hand edgeof said fabric, whereby fluid emerging under pressure from the outletends of said nozzles will impinge on said surface of said endless fabricbelt and will be directed substantially toward the lateral edges of saidendless fabric belt.
 2. A paper making machine as defined in claim 1wherein the angle between each said nozzle and said pipe means isbetween 10* and 60*.
 3. A paper making machine as defined in claim 2wherein the angle between each said nozzle and said pipe means isbetween 20* and 30*.
 4. A paper making machine as defined in claim 1where said fluid is water.
 5. A paper making machine as defined in claim1 where said fluid is air.
 6. A paper making machine as defined in claim1 wherein said nozzles provide a fish tail type spray having a widebottom impinging on said fabric, the length of said wide bottomextending in the width of said fabric; and wherein the bottoms of saidsprays of adjacent nozzles overlap one another to thereby providecleansing action over substantially the entire surface of the endlessfabric belt.
 7. A paper making machine as defined in claim 1 whereinsaid nozzles provide needle-type jet sprays, said spreader showeroscillating in the cross-machine direction of said endless fabric beltto provide cleansing action over substantially the entire surface of theendless fabric belt.
 8. A paper making machine as defined in claim 7 andfurther including intermediate cleansing nozzles extending at an angleof 90* from said pipe means in the direction of the surface of saidendless fabric belt.
 9. A paper making machine as defined in claim 1wherein said endless fabric belt comprises an upper run and a lower runand wherein said upper run comprises said high tension portion and saidlower run comprises said low tension portion, and wherein said spreadershower is disposed between said upper run and said lower run and closelyadjacent to said lower run, said nozzles of said spreader shower beingdirected toward the lateral edges of said lower run of said endlessfabric belt.
 10. A paper making machine as defined in claim 1 whereinsaid endless fabric belt comprises a synthetic material.